Geology of Mojave National Preserve: Mitchell Caverns

The spectacular decorations of Mitchell Caverns form one drip at a time.

Dripping decorations

Dripstone decorations form during the final stage in cave development,
after the water table lowers. Spaces formed in the rock when the water table
was higher are left high and dry as the cave drains. Air fills the cavities
and calcite decorations can begin to deposit.

Water picks up calcite and carbon dioxide as it trickles down through pores and cracks in the limestone above the cave. When the carbon dioxide enriched water reaches the open cave, the carbon dioxide gas escapes from the water, almost like opening a can of soda. This reduces the acidity in the water so that calcium bicarbonate cannot remain dissolved in the water. Microscopic layers of calcite are deposited drip by drip, forming intricate dripstone decorations.

The lighted interior of Mitchell Caverns.

Speloethems

Dripstone features in caves are called speleothems (from the Greek spelaion for cave and theme for deposit). Electric lighting in Mitchell Caverns transforms the speleothems into beautiful and eerie forms.

Stalactites. Notice that some of the stalactites have been broken, exposing their hollow interior structure.

Stalactites, stalagmites and more

Stalactites grow downward from the cave roof. Like other cave
formations, they form as water
slowly drips through cracks
in the cave ceiling. While each water drop hangs from the ceiling,
it deposits a calcite film.
After many thousands of years
and drips, an intricately decorated
hanging cone may form. Tubular
or "soda straw" stalactites grow in much the same way. Soda straws
are among the most fragile
cave decorations. They may
reach up to a yard in length, but have the diameter of a drop
of water.
Large stalactites begin as
these tiny soda straw tubes,then
gradually enlarge when water flows outside of the soda straws.

Stalagmites grow upward from the cave floor water when water drips
from overhanging stalactites or other ceiling decorations. In some
cases, stalactite and a stalagmite grow until they join, forming
a column. Cave drapery can form on sloped cave ceilings when the
drops of water trickle along an incline. A thin, curtain-like sheet
of calcite may grow along the slope, creating fragile, translucent
draperies.

Mitchell Caverns stalagmites

Sheets of calcite deposited on walls or floors by flowing water are called flowstone. Rimstone dams are raised fence-like deposits of calcite on the cave floor that form around pools of water.

Mitchell Caverns preserves excellent examples of these amazing cave decorations. See more in our image gallery.